As known in the art of imagesetting and electronic prepress systems, heretofore, output devices, e.g. imagesetters and more recently platesetters typically have been served by a dedicated Raster Image Processor (RIP) connected between a front-end and an output device. Typical electronic prepress image file sizes, e.g. often greater than 100 Megabytes per page, have previously restricted electronic prepress systems to dedicated proprietary hardware and software systems using parallel data transfer methods to provide high speed data transfer rates between the front-end, the RIP and the output device
More recently, use of page description languages, e.g. Postscript™ and PDF™, offered by Adobe Systems of Mountainview Calif., have allowed object oriented text descriptions of large image data files to be transferred efficiently over serial data communication lines, as used in network systems and adopted in electronic prepress systems, for transferring serial image data in page description formats between a front-end and a RIP. Serial data transfer systems offer the advantage that two way communications between the front-end and the RIP allow status information and other commands and files to be transferred in either direction as will be further described below.
Once the image file data is received by the RIP, operations such as image screening, color separating, imposition, trapping and various other prepress image preparation operations result in a final bit map image data file which heretofore has been transferred to the output device over a parallel data transfer interface in order to provide an efficient data transfer rate, thereby, keeping the output device operating at a desired operating speed. Typically, the process of RIPing data, i.e. preparing a final bit map image file for transfer to the output device, has been slow, sometimes causing the output device to remain idle while waiting for a RIP to prepare the next bit map image file.
Even more recently, the use of a RIP multiplexer, (MUX), e.g. MULTISTAR, offered by Agfa Corporation of Wilmington, Mass., has offered the electronic prepress industry some improvement in data throughput, and cost savings, by functioning as a page buffer between one or two RIPs, and a single output printing device. Cost savings and improved efficiency have been realized by either RIPing an image with a first RIP while transferring a previously RIPed image to the output device or by storing RIPed image data for transfer to the output device at an appropriate time after RIPing. This more fully utilizes the output device, or print engine, which is typically an expensive resource. In fact, keeping the print engine busy is a key design goal of any electronic prepress system design.
Typically, for electronic prepress and imagesetting systems of the prior art, a print job required that a specific output device be connected to the system before the job could be processed. For example, a print job requiring a particular imagesetter for an output device, (engine), or a particular media type or size loaded onto the output device, could not be processed into raster data, if the particular output device that was currently connected to the system did not meet the job requirements. Such a condition may cause a system delay or require that a front-end operator physically change the media or output device connected to the RIP in order to continue processing and outputing image files.
Since, the electronic and imagesetting systems of the prior art were not only device dependent but media dependent as well, the queuing of rasterized print jobs was not possible. Thus, the choice of the output device and print media proved to be a considerable hindrance in productivity.
Another expensive resource, front-end operators, are also kept busy since transfer of bit map image data between a RIP and a MUX has been controlled by the front end operator in the prior art system. Such operators are often the image creators and editors and burdening these operators with control of the output process reduces overall system efficiency. By moving control of the RIPing and image output process to a system administrator, the front end operator and the front-end itself become free to function more efficiently.
However, one of the biggest shortcomings of electronic prepress systems of the prior art, heretofore, has been the inability to control and monitor the queuing of output jobs and to make changes in the order or priority of image output either from the RIP of from the output device. Further, prior art systems have offered no user interface which might be used by a system administrator or a prepress shop manager to control the RIPing and output process. Furthermore, due to the costly proprietary hardware and inflexible nature of RIP and output engine hardware, few, but costly, expansion opportunities have been available for the prepress customer.
Another problem of the prior art has been that in order to transfer bit map data between a RIP and a MUX or between a MUX or a RIP and an output device, it has been necessary to use a parallel communication interface in order to provide data transfer rates which are fast enough for transferring very large image data files, e.g. image data files in excess of 100 Mbits per page, at rates which provide efficient workflow. Prior art bit map data parallel transfer interface systems, e.g. Agfa Printer Interface Standard (APIS) or Small Computer Systems Interface (SCSI) systems, use a data transfer protocol to identify the data file format and convert serial data into 8 bit parallel data formats. Then, the 8 bit data is transferred over parallel data interface cables which provide a plurality of separate wires bundled together, each transmitting data in parallel. However, since parallel data transfer methods are restricted to one way data transfer, e.g. between the RIP and MUX or between the MUX or RIP and an output device, a serial data channel has also been provided bundled within, or in addition to, the parallel data interface cable to provide two way communication for protocol and other message or file communication between the RIP and the MUX or between the RIP or MUX and the output device or between the front-end and the RIP, the MUX or the output device. One significant draw back of a parallel data transfer interface has been that the cable length is limited in order to maintain efficient and effective data transfer. In some operations, cable length may be limited to about 25 feet requiring that the RIP, MUX and output device each be locally connected to each other and usually all within the same room. This shortcoming of the prior art has limited prepress systems to local connectivity and slowed the development of automation features needed in modern prepress workflow environments. A need exits for better overall control of the RIP, MUX and output process by a system administrator. Features such as job queuing, equipment swapping, and manipulating, editing, storing and transferring previously RIPed bit map image data are needed in the modern prepress environment.
For electronic prepress systems which have employed imagesetters as print engines to create pages, typically, these devices have been driven by a dedicated RIP or a MUX. The RIP/Imagesetter or RIP/MUX/Imagesetter combination has been very productive in creating pages. Except for the most complex jobs, the RIP has advanced so that it is not the bottleneck in the pre-press workflow of page creation.
Today's needs for developing large format imagesetters (and platemakers and on-press plate imaging) go well beyond creating just pages. These devices produce press size flats in film or plate that may contain four, eight, or more pages. These devices have also been driven by a RIP or MUX, but unlike page format imagesetters, the RIP can be the bottleneck in creating press format films and plates.
As the needs of the electronic prepress industry steadily move towards large format imagesetters and the direct-to-plate workflow, it becomes imperative that the output devices be supplied data at rates which meet their specified throughput requirements. This means that the workflow system must be able to perform at or better than engine speed. Notwithstanding the advent of RIPs operating at faster processing speeds, direct RIP to engine configurations cannot guarantee meeting these requirements, especially as large-format, very complex jobs become more and more common.
In addition, with the advent of platesetters and direct-to-press prepress systems, a need also exists to provide a digital proofing device capable of providing either a color or black and white proof of the final image since films used to provide analog proofs have often been eliminated from the prepress workflow. Such proofing systems may accept image files as page description data, screened bit map data or bit map data which has not been screened. A need therefore exists to redirect image data to a proofer, and that data may need to be prepared in an appropriate format for output by the proofer.
Thus, there exists the need for an electronic prepress system that can meet these data requirements to drive an output engine at speed, to redirect appropriately formatted data to a proofer, to queue store or manipulate the priority of image output files and to provide overall control of the RIPing and output functions of a modern prepress system to a system administrator, while maintaining high amounts of “production time” at the front end workstations and the output devices.